Several prior patents and patent applications describe the use of an H-shaped belt as part of a mail holder and capable of ejecting the mail pieces from the open end of the holder. See U.S. Pat. No. 7,547,174 Method of Removing a Flat Article from a Holder and U.S. Pat. No. 7,138,596 Apparatus and Method for Mail Sorting, and U.S. Patent Publications 20070209976 and 20070017855 (Mail Sorting System).
The H-belt was used as part of an ejection mechanism in a sorting robot which delivers a mail piece to a slot in a sorting case and then ejects a carrier flat mail piece into the slot. It has been further proposed to sort mail pieces by first placing them into holders such as folders and sorting the folders.
U.S. Patent Publication No. 20070209976 describes a single pass mail sorting system wherein flat mail pieces are inserted into holders in the form of folders or bags doubled over a support rail, and the holders are sorted in order to sort the mail pieces contained inside. A holder of the present invention differs from the known H-belt holder in that it does not eject the mail piece in the sense of pushing it out of the holder; rather it withdraws the holder walls around it, leaving the mail piece exposed for removal.